The invention relates to a driving device for shutters, especially roller shutters, movable between a closed position and an open position, having a motor generating a rotational movement and optionally a drive, which motor and optionally drive, by means of driving elements, act on the shutter in the sense of setting it to the open position, having means which initiate an automatic transfer of the shutter into the closed position without the assistance of the motor, and having a braking element which decelerates the automatic movement of the shutter into the closed position under its dead weight.
In such a driving device intended for a fire-proof shutter, the braking element is provided in the form of a centrifugal brake which has a decelerating effect on the automatic movement of the shutter into the closed position under its dead weight (see brochure of Rolladenwerk Gebr. Effertz, Rheydt, "Elferrs Feuerschutz Rolltore", Druckzeichen 8.74). Such a centrifugal brake is complicated and expensive. When driving such a shutter it must be ensured that the closing movement is damped because the shutters consist of steel, comprise a considerable dead weight and in some cases considerable heights. The closing movement must be such as to avoid any damage, and furthermore, the braking element must not obstruct the return of the shutter into the open position. The closing movement under the dead weight of the shutter is essential because when a fire breaks out, for example, the closing function of the shutter must not depend on an energy source such as electric current.